Multi-position valves with reciprocating slide bars, or gates, are quite old in the art. Such valves are described in U.S. Pat. No. 2,394,487, granted Feb. 5, 1946, to L. C. Rotter et al; U.S. Pat. No. 2,485,504, granted Oct. 18, 1949, to M. Morgan; U.S. Pat. No. 2,858,851, granted Nov. 4, 1958, to J. W. F. Holl; U.S. Pat. No. 2,868,497, granted Jan. 13, 1959, to C. P. Graham; U.S. Pat. No. 2,998,828, granted Sept. 5, 1961, to R. C. Hare; U.S. Pat. No. 3,070,960, granted Jan. 1, 1963, to G. E. Ternent; U.S. Pat. No. 3,095,004, granted June 25, 1963, to J. G. Jackson, Jr., et al; U.S. Pat. No. 3,150,517, granted Sept. 29, 1964, to F. B. Kuffer et al; and U.S. Pat. No. 3,324,888, granted June 13, 1967, to R. J. Henderson.
The valve disclosed by U.S. Pat. No. 2, 394,487 is really two valves in one. The upper end of the valve (as shown in the patent drawings) is similar in its basic structure to the preferred embodiment of the present invention. However, the spring means for biasing the slide bar into an intermediate position is entirely absent. The patent does disclose a detent between the body and the slide bar for determining a neutral position.
The valve disclosed by U.S. Pat. No. 3,324,888 is similar in its basic structure to both the aforementioned valve of U.S. Pat. No. 2,394,487 and the valve of the present invention. Again, the spring means for biasing the slide bar is entirely absent. Detent means are provided in the two end positions but are absent in the intermediate position.
The principal object of the present invention is to provide an improved multi-position valve which has a slide bar biased by spring means into an intermediate position.
U.S. Pat. No. 3,070,960 discloses a synchronized hydraulic remote control system that includes a valve slide member with two free ends which are provided with centering springs for normally retaining the slide member in its central position.
The above described patents, together with the prior art that was cited and considered by the Patent Office before granting them, as listed on such patents, should be carefully considered for the purpose of properly evaluating the subject invention and putting it into proper perspective relative to the prior art.